1. Field of the Invention
The present invention relates to a composite sealing material to be used in sealing members for various valves, various pumps and the like.
2. Related Art Statement
Generally, valves set in pipes for steam, water, oil, chemicals and the like to be used in thermal power plants and the like, are arranged in very narrow spaces, high places, open-air spaces and the like. Therefore, it is very difficult to effect exchanging operations of sealing members of the valves. Moreover, various kinds of valves are used in the thermal power plants, and setting directions of the valves are varied as a horizontal direction, an inclined direction, a vertical direction and the like. From this point of view, it is also difficult to effect the exchanging operations of the sealing members.
As the sealing members mentioned above, a composite sealing material comprising an inner portion and an outer portion enveloping the inner portion, the inner portion being composed of a small ceramic discrete material and the like, and the outer portion being composed of a carbon base material, has been disclosed in Japanese Patent Laid-Open Publication Nos. 6-58,425 and 6-87,674 (U.S. patent application Ser. No. 8/68,674).
The composite sealing material mentioned above has at least a carbon outer portion, and thus it has sufficient sealing properties for the sealing members of the valves, pumps and the like mentioned above, since it is easily assembled and has good sealing properties. However, if the sealing member is formed by arranging a number of the composite sealing materials in a packing box, and pressing the composite sealing materials, the sealing members sometimes have insufficient sealing properties.